The proposed research is to examine the hypothesis that migratory fishes can orient to the earth's magnetic field and to the electric fields generated by ocean currents. The specific objectives, using American eels and Atlantic salmon, are to determine: (1) a conditioned behavioral d.c. electric current sensitivity threshold; (2) it the fishes can discriminate the po;arity of a weak d.c. electric field; (3) if the orientation of a weak electric or magnetic field can influence the fishes' body orientation; (4) if electroreceptors are present in the integument of eels.